3-D printing has been hailed as a technology that will transform manufacturing of everything from homes to organs. It’s, in a word, useful.

But a recent project explored the potentials of 3-D printing that are explicitly useless (or to put it less harshly, un-useful). As part of a project at the Art Hack Day event in Stocholm, Rickard Dahlstrand 3-D printed music. Using a Lulzbot 3-D printer and some microphones, he was able to simultaneously perform and “print” music, creating unique pieces that visualize classic musical works.

On Vimeo, Dahlstrand writes: “People have been playing music on their 3-D printers for ages. I wanted to see what it would look like printed. It turned out to be really interesting.”

How exactly does a 3-D printer play music? The “stepper motors” that power the printer play different pitches when moving at different speeds. Making music on steppers–through decoding MIDI files of songs into a form of data that tells the motors how to move to recreate those pitches–is a classic geek move. (YouTube is littered with videos of dudes playing video game themes on stepper motors, for example.)

But the unique thing about this project is that, as the printer’s motors move along three different axes, they extrude an object in plastic at the same time. In Dahlstrand’s words: “The stepper motors controlling the movement can be run at different speeds. The speed decides the pitch of the sound and makes it possible for the motors to make music.”

So each piece–which included Johan Strauss’s “Blue Danube,” Star Wars composer John William’s classic, the “Imperial Death March,” and the “Habanera” from Georges Bizet’s opera Carmen–yields a distinct object, a physical and permanent infographic object of an otherwise ephemeral chunk of sound.ZS